Has anybody ever replaced the HVAC Programmer? - Page 3 - ZR-1 Net Registry Forums

S.hafsmo · 03-12-2017

Strange. Did you try asking WVZR-1 to check differences between the pin-outs for those model years?

QB93Z · 03-12-2017

In the FSM, under the Symptom: HVAC Programmer is not functional, there is a diagnostic procedure to measure voltage on most of the connections between the Programmer and the connectors and to the Door Motor. Unfortunately I have not been able to get the Programmer out to where I can remove the connecter or get a probe to accurately back-probe the wires.

If my harness change does not solve the problem, I will have to begin disassembly of the components in the driver's side foot well so I can access the Programmer.

Jim

S.hafsmo · 03-12-2017

Is it a 94 FSM you're using? If so, I can post the connector pin-outs from my 90 FSM (think they're the same as 91) if you'd like to compare them. Should give you a good hint to whether or not the harness is the same.

Sent from my SM-T719 using ZR-1 Net Registry mobile app

Roadster · 03-12-2017

Jim, did some research....maybe you have already seen this, from CAC in 2006.

"HVAC Programmer/Temp Door Fixed!

Well, I am pleased to report that the temperature door on my '89 Ebay rat is now fixed after much study and many questions (it wasn't working when I got the car, notwithstanding the claims of the electrical engineer who said it was fixed by him----go figure). The problem was that, as I suspected, the HVAC programmer was bad. I replaced the programmer with a new one from gmpartsdirect.com this weekend, and gritted my teeth as I switched the controller from full air conditioning to full heat. Voila! It was one those triumphal moments that I am sure you can all appreciate. So, the lesson is this: If everything works on the electronic HVAC system except that the temperature door does not swing from full by-pass of the heater core to flow through the heater core, then the problem is probably the HVAC programmer. From some tests I ran it also appears that the temperature door does an automatic default to full by-pass of the heater core if the programmer is defective. Here in Houston, it was 80 degrees yesterday, so the rat and I went down to Galveston to go surfing and we ran into a dense fog bank (virtually no surf and no visibility cancelled surf plans). The outside temperature dropped about 15 or more degrees within three miles from the beach, so I got a chance to try out the heater for real. It seems to work great!

/s/ Chris Kennedy
Houston, Texas"

Also a link for a remanufactured HVAC Programmer if you do in fact need one....
https://corvetteparts.com/item/progr...tion-1994-1995

Roadster · 03-12-2017

Some other links.....

http://www.ebay.com/itm/AC-HEATER-PR...del%3ACorvette

http://www.ebay.com/itm/1994-1995-C4...del%3ACorvette

Also a video on rebuilding the complete system....the head unit, the blend door and the HVAC programmer.

https://www.bing.com/videos/search?q...47EE&FORM=VIRE

And blend door repair kit for the gear, couldn't find anything on the motors....

http://blenddoor.com/product/gm-blen...r-rebuild-kit/

QB93Z · 03-18-2017

I believe that I have solved all the problems with the HVAC system. This afternoon I got cool air from the dash vents when it should, warm air from the floor vents when heat was needed, and air blowing on the windshield only when it was supposed to.

As a summary, the problems that I corrected were:

1. A pinched vacuum line to the HVAC Programmer Module. This caused sluggish or no operation of the vent system dampers so the air would blow in the wrong places. Repaired by adding an elbow and rerouting the tubing.

2. Damaged electrical connector at the vent blower control resistor. This caused intermittent operation of the vent blower. I replaced the connector.

3. A failed Blend Air Door Motor. This caused the HVAC system to never add warm air when heat was required. I replaced the motor.

I did solve why I had the problems with the Blend Air Door Motor. During my trouble shooting of the failed motor, I tried to install the motor from a 1991 system. I deduced that the motor had to turn in the opposite direction than in a 1991 system because the location of the motor was changed in 1994 and after from the top of the duct to the bottom of the duct. I tried swapping the +DC and -DC wires in the wiring harness to the motor. The 1991 motor did not work at all with that wiring. I bought a 1994 motor and installed it. Since the 1994 wiring pigtail had the swapped wires. I used the 1991 harness pigtail. --- Big Mistake-- Every motor I tried operated, but in the opposite direction to what was required. It took me a week and a lot of research to figure out that I had introduced the problem since the 1991 harness pigtail was wired differently from the 1994 pigtail. Today, I restored the + and - wires in the 1994 pigtail, and the system works with the 1994 motor.

Adding to the confusion of the motors is that the 1991 and the 1994 motors have the same GM Part number (16124952), and look the same, but they are wired differently internally.

It has been an excellent learning experience and now I can reassemble the interior and move on to the next project.

Jim

S.hafsmo · 03-18-2017

Well done, Sir.
Appreciate you taking the time to sum it up for the rest of us.

Sent from my SM-T719 using ZR-1 Net Registry mobile app

secondchance · 03-18-2017

I am a bit confused. Why did you try to use 91 harness?
Nonetheless, great to know that we have HVAC specialist within the WAZOO.
Great job!

secondchance · 03-18-2017

Jim,

One question - any idea what caused moisture build up around the motor? Poor design? Any way to avoid motor corrosion? Do you see motor corrosion as being unavoidable for later Zs with AC operation?

QB93Z · 03-18-2017

I used the 1991 harness when I got the 1994 motor from eBay. I didn't give a thought to possibility that it might be different. To me at the time, it was just a connection to the harness from the Programmer. Two demerits for sloppy trouble shooting.

Regarding the corrosion in the old motor. The water must come from the condensation in the AC evaporator. The condensation must collect in the duct and then overflow the opening for the blend door shaft, into the motor. I plan to figure out where the evap drain line is and make sure it is not plugged. The motor is not watertight at all. Water leaking around the operating shaft would drip onto the passenger hush panel and then onto the passenger carpet just like a heater core leak. Now that I think about it, the moisture in the motor could be coolant from the heater core. But I have never had evidence of a heater core leak.

More things to investigate...

Jim

03-12-2017	#21
S.hafsmo Join Date: Nov 2016 Location: Norway Posts: 397	Re: Has anybody ever replaced the HVAC Programmer? Strange. Did you try asking WVZR-1 to check differences between the pin-outs for those model years? __________________ - '90 ZR-1

03-12-2017	#22
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,689	Re: Has anybody ever replaced the HVAC Programmer? In the FSM, under the Symptom: HVAC Programmer is not functional, there is a diagnostic procedure to measure voltage on most of the connections between the Programmer and the connectors and to the Door Motor. Unfortunately I have not been able to get the Programmer out to where I can remove the connecter or get a probe to accurately back-probe the wires. If my harness change does not solve the problem, I will have to begin disassembly of the components in the driver's side foot well so I can access the Programmer. Jim

03-12-2017	#23
S.hafsmo Join Date: Nov 2016 Location: Norway Posts: 397	Re: Has anybody ever replaced a HVAC Programmer? Is it a 94 FSM you're using? If so, I can post the connector pin-outs from my 90 FSM (think they're the same as 91) if you'd like to compare them. Should give you a good hint to whether or not the harness is the same. Sent from my SM-T719 using ZR-1 Net Registry mobile app __________________ - '90 ZR-1

03-12-2017	#24
Roadster Join Date: Mar 2014 Location: Warrington PA Posts: 1,914	Re: Has anybody ever replaced the HVAC Programmer? Jim, did some research....maybe you have already seen this, from CAC in 2006. "HVAC Programmer/Temp Door Fixed! Well, I am pleased to report that the temperature door on my '89 Ebay rat is now fixed after much study and many questions (it wasn't working when I got the car, notwithstanding the claims of the electrical engineer who said it was fixed by him----go figure). The problem was that, as I suspected, the HVAC programmer was bad. I replaced the programmer with a new one from gmpartsdirect.com this weekend, and gritted my teeth as I switched the controller from full air conditioning to full heat. Voila! It was one those triumphal moments that I am sure you can all appreciate. So, the lesson is this: If everything works on the electronic HVAC system except that the temperature door does not swing from full by-pass of the heater core to flow through the heater core, then the problem is probably the HVAC programmer. From some tests I ran it also appears that the temperature door does an automatic default to full by-pass of the heater core if the programmer is defective. Here in Houston, it was 80 degrees yesterday, so the rat and I went down to Galveston to go surfing and we ran into a dense fog bank (virtually no surf and no visibility cancelled surf plans). The outside temperature dropped about 15 or more degrees within three miles from the beach, so I got a chance to try out the heater for real. It seems to work great! /s/ Chris Kennedy Houston, Texas" Also a link for a remanufactured HVAC Programmer if you do in fact need one.... https://corvetteparts.com/item/progr...tion-1994-1995 __________________ Tom 1994 ZR-1 #009 "captured test fleet car" 1974 LS4 454 Vert 1974 L-82 355 Vert. 1982 L83 CFI...now a retired "dd"....Sold WAZOO Member

03-12-2017	#25
Roadster Join Date: Mar 2014 Location: Warrington PA Posts: 1,914	Re: Has anybody ever replaced the HVAC Programmer? Some other links..... http://www.ebay.com/itm/AC-HEATER-PR...del%3ACorvette http://www.ebay.com/itm/1994-1995-C4...del%3ACorvette Also a video on rebuilding the complete system....the head unit, the blend door and the HVAC programmer. https://www.bing.com/videos/search?q...47EE&FORM=VIRE And blend door repair kit for the gear, couldn't find anything on the motors.... http://blenddoor.com/product/gm-blen...r-rebuild-kit/ __________________ Tom 1994 ZR-1 #009 "captured test fleet car" 1974 LS4 454 Vert 1974 L-82 355 Vert. 1982 L83 CFI...now a retired "dd"....Sold WAZOO Member Last edited by Roadster; 03-12-2017 at 11:13 PM.

03-18-2017	#26
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,689	Re: Has anybody ever replaced the HVAC Programmer? I believe that I have solved all the problems with the HVAC system. This afternoon I got cool air from the dash vents when it should, warm air from the floor vents when heat was needed, and air blowing on the windshield only when it was supposed to. As a summary, the problems that I corrected were: 1. A pinched vacuum line to the HVAC Programmer Module. This caused sluggish or no operation of the vent system dampers so the air would blow in the wrong places. Repaired by adding an elbow and rerouting the tubing. 2. Damaged electrical connector at the vent blower control resistor. This caused intermittent operation of the vent blower. I replaced the connector. 3. A failed Blend Air Door Motor. This caused the HVAC system to never add warm air when heat was required. I replaced the motor. I did solve why I had the problems with the Blend Air Door Motor. During my trouble shooting of the failed motor, I tried to install the motor from a 1991 system. I deduced that the motor had to turn in the opposite direction than in a 1991 system because the location of the motor was changed in 1994 and after from the top of the duct to the bottom of the duct. I tried swapping the +DC and -DC wires in the wiring harness to the motor. The 1991 motor did not work at all with that wiring. I bought a 1994 motor and installed it. Since the 1994 wiring pigtail had the swapped wires. I used the 1991 harness pigtail. --- Big Mistake-- Every motor I tried operated, but in the opposite direction to what was required. It took me a week and a lot of research to figure out that I had introduced the problem since the 1991 harness pigtail was wired differently from the 1994 pigtail. Today, I restored the + and - wires in the 1994 pigtail, and the system works with the 1994 motor. Adding to the confusion of the motors is that the 1991 and the 1994 motors have the same GM Part number (16124952), and look the same, but they are wired differently internally. It has been an excellent learning experience and now I can reassemble the interior and move on to the next project. Jim Last edited by QB93Z; 03-18-2017 at 07:04 PM.

03-18-2017	#28
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,721	Re: Has anybody ever replaced the HVAC Programmer? I am a bit confused. Why did you try to use 91 harness? Nonetheless, great to know that we have HVAC specialist within the WAZOO. Great job!